 # Single pressure reading.  This message is appropriate for measuring the
 # pressure inside of a fluid (air, water, etc).  This also includes
 # atmospheric or barometric pressure.

 # This message is not appropriate for force/pressure contact sensors.

 Header header           # timestamp of the measurement
                         # frame_id is the location of the pressure sensor

 float64 fluid_pressure  # Absolute pressure reading in Pascals.

 float64 variance        # 0 is interpreted as variance unknown